Simplify the following expression: $y = \dfrac{1}{7t} + \dfrac{1}{6t}$
Solution: In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $7t$ and $6t$ $\lcm(7t, 6t) = 42t$ $ y = \dfrac{6}{6} \cdot \dfrac{1}{7t} + \dfrac{7}{7} \cdot \dfrac{1}{6t} $ $y = \dfrac{6}{42t} + \dfrac{7}{42t}$ $y = \dfrac{6 +7}{42t}$ $y = \dfrac{13}{42t}$